Received this the other day, but wrong TPI for my 300, and the company I bought it from will not accept returns. The thread pitch is set up for a barrel with a 9/16 x 24 thread pitch. You can see the list of accepted calibers in the picture, and I could get some better pics up tomorrow. I'm asking 125, PayPal friends or family, or you pay the fees. Please email me or best response.